Several mouse models of muscular dystrophy will be used extensively by all investigators. Much of this work can be most efficiently handled by a core that provides various services, including maintenance of the mouse colonies, breeding, and genotyping. In addition, muscle physiology studies important for testing rescue of the dystrophic phenotype will be carried out in the core, as will injection of both viral vectors and transduced stem cells. Finally, the core will perform creatine kinase and/or pyruvate kinase assays for identification of suppressor mutations following mutagenesis of the mdx mice.